KR101640627B1 - Photovoltaic array with minimally penetrating rooftop support system - Google Patents

Abstract

The photovoltaic array of the present invention includes a plurality of photovoltaic assemblies and a plurality of mounting units. Each of the mounting units includes a long rail and a plurality of leg assemblies. The rails are sized and configured to hold at least a portion of at least two photovoltaic assemblies of the photovoltaic assembly, the leg assemblies extending from the rails in a spaced manner and leading to the base to be positioned relative to the rooftop structure for minimal through installation. Also, at least one of the leg assemblies may include retractable legs. When the photovoltaic array is installed in a rooftop structure that includes a membrane intermittently secured to the roof deck, the inflatable leg accommodates the upward wave swing of the membrane under wind conditions.

Description

[0001] PHOTOVOLTAIC ARRAY WITH MINIMALLY PENETRATING ROOFTOP SUPPORT SYSTEM [0002]

The present invention was made with Government support under Contract No. DE-FC36-07GO17043 awarded by the US Department of Energy. The Government has certain rights in the invention.

The present invention relates to a roof mounted photovoltaic array. More particularly, the present invention relates to a minimum penetrating support system for installing an array of photovoltaic elements in a rooftop structure, such as a lightweight commercial building.

Solar power has long been regarded as an important alternative energy source. For this reason, considerable efforts and investments have been made in developing and advancing solar energy collection technologies, particularly photovoltaic technology. As the cost of solar cells has decreased, non-solar cell components, which are essential for maintaining the photovoltaic system for the installation site, have begun to influence the overall system cost. Of particular interest is the application of industrial or commercial forms, where a considerable amount of solar energy can be collected, but the corresponding installation / support system costs may adversely affect potential user purchasing decisions.

Photovoltaic cells are the underlying technology for photovoltaic solar energy collection. Typically, a series of photovoltaic cells and arrays of photovoltaic cells are formed on a single panel or stack. The resulting photovoltaic stack can then be assembled to a frame (and other components) to create a photovoltaic module. Alternatively, two or more photovoltaic stacks may be assembled in a common frame. Regardless of whether a photovoltaic stack or photovoltaic module is supplied (collectively referred to as a "photovoltaic device"), most photovoltaic applications utilize a photovoltaic Lt; / RTI > This is particularly suitable in the case of commercial or industrial applications where a relatively large number of photovoltaic devices are desirable to generate a significant amount of energy on the roof of a commercial building that provides a good surface for the photovoltaic element to be installed on. From a reference point of view, many commercial buildings have a large flat roof that essentially contributes to the placement of photovoltaic arrays and makes the most realistic use of space. Thus, although the rooftop installation is very practical, various limitations of the mounting system employed for holding the photovoltaic device should be considered. For example, because the installed photovoltaic array is subject to an upward force (e.g., wind) and a downward force (e.g., mass of the array, eye, etc.), the mounting system, under these circumstances, To maintain a solid connection with the system.

There are two main types of photovoltaic mounting systems used with flat commercial roofs. The standard rack system uses heavy and long rails secured to the roof by a number of roof penetrations (e.g., bolts running through or through the roof structure). These systems are typically designed to withstand wind load calculations using standard methods. While available photovoltaic roof top rack systems can firmly support and support multiple photovoltaic elements, rooftop penetrations are not desirable (either by creating an opportunity for leaks or otherwise altering the original appearance of the roof permanently) It can be very heavy. Thus, a typical rack system in a lightweight building may not be usable. Conversely, a lightweight non-penetrating roof mounting system has been developed that relies on pressure equalization to avoid the obvious load imposed by pressure fluctuations on the building exterior. These non-penetrating systems are typically designed using a wind tunnel method to ensure that high wind speeds do not cause failure.

Lightweight non-penetrating photovoltaic array mounting systems can significantly reduce the amount of labor and materials for installation and can cause the number of penetrations into the roof contour to be very small or even absent, but there are still problems in certain applications do. In particular, many lightweight commercial buildings incorporate rooftop structures with membranes mechanically attached to the underlying roof deck. The membrane is limited and connected to the roof deck at a spaced pinning point. Pressure fluctuations on the roof will cause the unattached sections of the membrane to vibrate strongly or swell. Under such circumstances, a waveowing membrane can cause failure in the non-penetrating photovoltaic array mounting system, in other ways, because the mounting system connection points located on the wave swing membrane impression are greatly curved It can cause problems. A batten bar refurbished to retain the membrane on the roof deck at regular intervals may be employed, but since these barten bars are expensive, labor intensive in installation and require many rooftop perforations, the " Non-penetrating "mounting system.

In view of the foregoing, there is a need for a minimally penetrated photovoltaic roof support system that maintains structural integrity in the presence of a variety of forces, including wavy bump membranes.

Some aspects in accordance with the present invention are directed to a photovoltaic array comprising a plurality of photovoltaic elements and a plurality of mounting units. Each photovoltaic element includes at least a photovoltaic stack. The mounting unit is provided to support the photovoltaic element with respect to the roof structure, each comprising a long rail and a plurality of leg assemblies. The rails are sized and configured to hold a portion of at least two of the photovoltaic elements, and the leg assemblies extend from the rails in a spaced manner. Also, each of the leg assemblies is terminated at the base against the rails for positioning to the roof structure. At least one of the leg assemblies includes an inflatable leg configured to permit movement of the opposing base toward the rails in response to an applied external force. Thereafter, in such a construction, if the photovoltaic array is installed in a roof structure comprising a membrane intermittently secured to the roof deck, the inflatable leg is capable of generating an upward wave swing of the membrane normally occurring under wind conditions Accept. In some embodiments, the rails are lightweight and sized to support multiple photovoltaic elements in a spaced apart arrangement to enhance pressure equalization. In another embodiment, at least two of the leg assemblies that cooperate with the mounting unit incorporate a rigid leg that can be coupled to the roof structure by a through-fastener.

Another aspect of the invention relates to a method for installing a photovoltaic array in a commercial building rooftop structure comprising a membrane coupled to a rooftop deck at intermittent pinning points. The method includes providing a mounting unit including a long rail, a plurality of mounting leg assemblies, and at least one support leg assembly. Each leg assembly extends from the rails and terminates at a base opposite the rails. Also, the leg elements are arranged along the length of the rail in a spaced manner. The mounting unit is disposed relative to the roof structure such that each base contacts the membrane and the rails are spaced above the membrane. The bases of each of the mounting leg assemblies are each fastened to the roof structure by at least one fastener penetrating through the membrane to the roof deck. Finally, at least two photovoltaic elements are mounted on the rails to hold the photovoltaic elements such that the mounting units are spaced therefrom over the membrane. By this method, in the final installation, the base of the at least one support leg assembly is not coupled to the roof structure by the through fastener. In some embodiments, the mounting unit includes a plurality of support leg assemblies, each of which is not coupled to the roof structure by a through-fastener. In addition, the penetration fastening portion is selectively employed only at the pinning point position of the membrane in the roof deck. With this method, thereafter, a minimum through penetration is achieved, thereby providing adequate support for the photovoltaic device under upward force and downward force conditions while minimizing the potential damage of the roof membrane. In another embodiment, the at least one support leg assembly provided with the mounting unit comprises a retractable leg, and the corresponding base is positioned above the non-finishing section of the membrane. In this installation technique, the retractable support leg assembly supports the photovoltaic array against downward forces, but allows or accommodates upward forces, such as, for example, lifting during membrane swing.

Another aspect in accordance with the present invention is directed to a method for providing a photovoltaic array for mounting to a commercial building rooftop structure that otherwise includes a membrane coupled to a rooftop deck at intermittent pinning points. The method includes determining a pinning distance between adjacent pinning points along a rooftop structure. The long rail is configured and configured to receive and hold a part of each of the plurality of photovoltaic elements. The two or more leg assemblies are mounted to the rails in a spaced-apart manner with a distance between adjacent leg assemblies corresponding to the determined peening distance. The photovoltaic array thus prepared can perform minimal through-installation to the roof structure, and the mounting unit leg assemblies are selectively fastened in a penetrating manner located at the rooftop structure at the pinning point, which is only the actual membrane.

1 is a simplified plan view of a photovoltaic array in accordance with the principles of the present invention.
Figure 2 is a simplified side view of the mounting unit portion of the photovoltaic array of Figure 1;
Figure 3a is a cross-sectional view of one structure of a rail portion of the mounting unit of Figure 2, which holds two photovoltaic elements.
Figure 3b is a cross-sectional view of another useful rail with the mounting unit of Figure 2;
Figure 4a is a simplified view of a typical lightweight building rooftop structure.
Figure 4b shows the wave swinging of a portion of the support structure of Figure 4a.
Figure 5a is an exploded view of the mounting unit of Figure 2 and the roof structure of Figure 4a.
Figure 5b shows the installation of a mounting unit in the roof structure of Figure 5a.
Figure 5c shows the installation of Figure 5b under wind conditions.
Figure 5d shows another installation of the roof structure and mounting unit of Figure 5a.
6A is a simplified view of another typical lightweight building rooftop structure.
Figure 6b shows the installation of a mounting unit in accordance with the principles of the present invention for the rooftop structure of Figure 6a.
Figure 7a is a simplified side view of another mounting unit in accordance with the principles of the present invention.
Figure 7b shows the installation of the mounting unit of Figure 7a for the roof structure of Figure 5a.
Figure 7c shows the installation of the mounting unit of Figure 7a for the roof structure of Figure 6a.
8A is a simplified side view of another mounting unit in accordance with the principles of the present invention.
Figure 8b shows the installation of the mounting unit of Figure 8a for the roof structure of Figure 5a.
Figure 8c shows the installation of Figure 8b under wind conditions.

One example of a photovoltaic array 20 in accordance with the principles of the present invention is shown in FIG. In some embodiments, the array 20 comprises a plurality of photovoltaic devices 22 configured for installation in a commercial building rooftop structure and formed and maintained in an array by a support system 24. Details of the various components are provided below. In general, however, the support system 24 is lightweight and provides a long-term support to the photovoltaic element 22 and provides a minimum of structural support to the rooftop structure in a manner that accommodates conventional rooftop structure deformations, Facilitates penetration mounting.

The photovoltaic element 22 may be implemented in various forms that may or may not be associated with FIG. Each photovoltaic device 22 includes a photovoltaic stack or panel 30 incorporating an array of photovoltaic cells. For environmental protection, a glass laminate can be placed on the photovoltaic cell. In some configurations, the photovoltaic cell advantageously includes a backside-contact cell of the type available from SunPower Corp. of San Jose, California, for example. do. Other types of photovoltaic cells of any type in the future that are currently known or otherwise developed appropriately for use as solar voltaic devices may also be employed without compromising the advantages of the present invention. For example, photovoltaic cells can incorporate thin film technologies, such as silicon thin films, non-silicon based devices (e.g., III-V cells including GaAs), and the like. Further, although not shown, in some constructions, each photovoltaic element 22 may include one or more components, such as wiring or other electrical components (not shown), in addition to the photovoltaic stack 30. Each of the photovoltaic devices 22 is a photovoltaic module in which the photovoltaic stack 30 is mounted on or maintained by a separate frame (i.e., a frame spaced from the support system 24) / RTI >

Recalling the foregoing description of the photovoltaic element 22, the support system 24 retains the photovoltaic elements 22 arrayed in the depicted format and provides a photovoltaic element 22 with a mounting structure (e.g., 22). The support system (24) includes a plurality of mounting units (40). The mounting units 40 are arranged in a side-by-side manner, and may be the same in some embodiments. The various structures of the mounting unit 40 embodied by the present invention are provided below. 2, each mounting unit 40 includes a rail 42 and a plurality of leg assemblies 44. As shown in FIG. The rail 42 is configured to receive and maintain a portion of the plurality of photovoltaic elements 22. Each of the leg assemblies 44 includes legs 46 extending from the rails 42 and terminating at the base 48, although they may or may not be the same. The leg assembly 44 serves to keep the rail 42 and thus the photovoltaic device 22 (see FIG. 1) mounted thereon in a spaced-apart position relative to the base 48.

The rails 42 provide a long body to hold the various photovoltaic devices 22 and can have a length of at least about 10 feet, in some embodiments at least 25 feet, and in another embodiment at least 50 feet . Thus, depending on the size and shape of the photovoltaic device 22, the rails 42 can hold a plurality of photovoltaic devices 22 (e.g., ten or more). In this regard, the rails 42 may be formed of a single homogeneous structure or may be composed of two or more separately formed rail segments that are assembled together. Thus, depending on the size and shape of the photovoltaic device 22, the rails 42 can hold a plurality of photovoltaic devices 22 (e.g., ten or more). Also, the rails 42 may have other lightweight structures of rigidity and may be configured to accommodate the photovoltaic devices 22 in a variety of ways. For example, FIG. 3A illustrates one embodiment of a rail 42 that holds the first and second photovoltaic devices 22a, 22b. The rail 42 has a tubular structure that defines opposed slots 50a, 50b sized to slidably receive each one of the photovoltaic elements 22a, 22b. The photovoltaic elements 22a and 22b are shown as a frameless laminate wherein the slots 50a and 50b are sized according to the frame of the module for ease of trapped final assembly . In some arrangements, the mounting unit 40 also includes a connector 52 for mounting the photovoltaic elements 22a, 22b on the rail 42. In a related embodiment, the connector 52 is electrically conductive and the rail 42 forms a wireway 54a, 54b to which a string wiring bus (not shown) may be connected. Fig. 3b shows another structural rail 42 'with its own string wire bus 56. Fig.

1 and 2, the rail 42 may incorporate various other features that facilitate the captive mounting of the photovoltaic element 22 thereto. For example, rail 42 is shown capturing the edge portion of each photoconductive element 22 of photovoltaic element 22, but in another embodiment, rail 42 is located below a series of photovoltaic elements 22 As shown in FIG.

Regardless of the exact cross-sectional shape of the rail 42, the rail 42 is very light compared to a conventional roof-top rack system. From a reference point of view, a roof top rack system is typically designed to withstand the maximum expected elevated load related to the intended installation location, calculated by standard methods. However, in an embodiment of the present invention, the rails 42 may be lighter than may otherwise be required to fully comply with the calculated maximum lift load, for the following reasons. The rails 42 may be made of aluminum, steel, or other lightweight yet rigid material. Regardless, in the lightweight construction, the rail 42 exhibits a minimum load relationship when installed in a roof structure.

1, support system 24 incorporates a lightweight rail 42 by forming an array such that a space or gap is provided between adjacent ones of the photovoltaic elements 22, And appropriately supports the photovoltaic device 22 against the upward force. For example, the array of FIG. 1 may be formed by disposing photovoltaic elements 22 in columns 60 and rows 62. For each row 60, the support system 24 maintains adjacent ones of the photovoltaic devices 22 such that a gap 64 is present. The size of the gap 64 can be selected as a function of the size of the photovoltaic element 22, but is typically about 1/8 inch to 1/4 inch. Regardless, the gap 64 allows for airflow / pressure to be generated from below the array, thus achieving pressure balance in the presence of a windy condition. Alternatively, adjacent photovoltaic elements of the photovoltaic elements 22 may be disposed closer together along each rail 42. [ 1 also shows an array 20 comprising twenty photovoltaic elements 22 (i.e. each row 60 includes five photovoltaic elements 22 and each row 62 ) Has four photovoltaic devices), any other number, larger or smaller numbers may be allowed. On the same line, column 60 and / or row 62 need not be the same. Finally, the rail 42 may be configured to hold the photovoltaic device 22 in the illustrated horizontal orientation (e.g., parallel to the plane of the rail 42) Parts can be integrated.

Recalling the foregoing understanding of the rail 42, the leg assembly 44 may implement any shape related to FIG. In general, the leg assemblies 44 are disposed in a spaced apart manner along the length of the rails 42 and may or may not be the same. In this regard, the selected structure of each leg assembly 44 is based on the intended function of the particular leg assembly 44 at the time of final installation in the roof structure. More specifically, each of the leg assemblies 44 will be simply placed in contact with the roof top structure (i.e., "mounting leg assembly") or through the roof top structure without through fasteners , Support leg assembly). In some embodiments, the leg assemblies 44 are the same, with functional application provided by the installer's decision as to whether to use a through-fastener to mount the base 48 to the roof structure (e.g., When the fasteners are used, the corresponding leg assemblies 44 act as mounting leg assemblies, and when the through fasteners are not used, the leg assemblies 44 serve as support leg assemblies. Leg 46 may be a rigid solid body (e.g., metal) and base 48 may be configured to enhance attachment with one or more fasteners (e. G., Bolts) So that one or more bores can be formed. Regardless, the mounting leg assembly structure exhibits structural stiffness under the anticipated force exerted on the mounting unit 40 (e.g., the upward force and downward force applied to the rail 42).

Various structures of the leg assembly 44 according to the present invention are described below. For a basic structure in which all of the leg assemblies 44 are the same and are adapted for use as mounting leg assemblies, the photovoltaic array 20 can be easily installed on a lightweight commercial roof. 4A is a simplified diagram of a lightweight commercial building rooftop structure 100 that includes a support beam 102, a roof deck 104, and a membrane 106. In this embodiment, The deck 104 is mounted across the beams 102 and the membrane 106 is secured to the outer surface of the deck 104. In some building manufacturing techniques, the membrane 106 is connected to the deck 104 at a spaced-apart pinning location 108. The connection formed in the peening location 108 may be accomplished in a variety of ways, but typically includes one or more fasteners (e.g., one or more fasteners) through the membrane 106 and through a corresponding one of the beams 102 Screws, nails, etc.). The peening location 108 may be evenly or randomly spaced and may indicate a real change portion of the rooftop structure 100 prior to installation of the photovoltaic array 20 (see FIG. 1). For example, the rooftop structure 100 shown in FIG. 4A includes first through fourth pinning positions 108a through 108d. In one such commonly employed technique, however, the peening positions 108a through 108d are equally spaced by a peening distance D, for example, approximately 10 feet. Defects are formed in the membrane 106 of each peening position 108, independently of the installation of the photovoltaic array 20, although the sealing element is typically applied. In addition, under wind conditions, the membrane 106 may swing from the deck 104 between adjacent peening locations 108, for example, as shown in FIG. 4B.

The photovoltaic array embodiment of the present invention can be configured to minimize the number of additional rooftop penetrations required for installation in the roof structure 100 and to accommodate wave swing of the membrane in the final installation. For example, FIG. 5A shows the mounting unit 40 prior to installation on the rooftop structure 100. The spacing between adjacent leg assemblies of the leg assemblies 44 is formed as a function of the corresponding pinning distance D (see FIG. 4A) between adjacent ones of the peening positions 108. More specifically, the mounting unit 40 is constructed by first evaluating or determining the pinning distance D between adjacent peening positions of the peening positions 108. Recalling the pinning distance D described above, the mounting unit 40 is then configured to include an appropriate number of leg assemblies 44 that are required for long term support of the photovoltaic array (not shown). The number of leg assemblies 44 may be determined for a particular installation site based on a calculated force (e.g., total array mass and expected gust), or may be determined based on known notifications that can fully support any array under extreme conditions Lt; / RTI > For ease of description, the mounting unit 40 is shown with four leg assemblies 44a-44d, but any other number, larger or smaller number may be equally applicable. Regardless, the space between each leg assembly 44a-44d corresponds to a peening distance D (e.g., 10 feet between the first and second leg assemblies 44a and 44b). In such a structure, when installing the mounting unit 40 in the roof structure 100 as part of the photovoltaic array, the leg assemblies 44a-44d are positioned in the respective peening positions 108a-108d, as shown in FIG. ≪ / RTI > Installation is accomplished by one or more fasteners (not shown) through the membrane 106 and through deck 104 and a corresponding one of the beams 102 to the roof structure 100, And fastening the base 48 of the assemblies 44a-44d.

In the final installation, the fixed relationship of the leg assemblies 44a-44d to the rooftop structure 100 is such that it is resistant to the upward force applied to the corresponding photovoltaic array 20 (see FIG. 1) Lt; / RTI > When the through-fastener is employed, this membrane penetration is formed only at the position where the membrane 106 is pre-pierced (i.e., the peening position 108a to 108d). Thus, the structure of FIG. 5B acts as a minimal through installation. Also in the windy state, the installed mounting unit 40 does not inhibit the "normal" wave swing of the membrane 106 shown in Fig. 5C. The leg assemblies 44a-44d may be mounted on the rails 42 at a height "above " the maximum wobbling height of the membrane 106 so that the wobbly membrane 106 does not exert significant force on the rails 42. [ .

The installation of Figure 5b includes that each of the leg assemblies 44 is mounted to the roof structure 100 by way of fasteners so that both of these leg assemblies act as mounting leg assemblies, The one or more leg assemblies 44 need not be mounted directly on the roof structure 100. Based on an estimate of the expected wind induced upward force to be experienced, for example, by photovoltaic array 20 (see FIG. 1), a small number (e.g., fewer than total) It can be concluded that only the leg assemblies 44 of the legs 44 need to be mounted directly. 5d shows that only the first and third leg assemblies 44a and 44c are mounted directly to the roof support structure 100 by the through fasteners while the second and fourth leg assemblies 44b and 44d are simply (Acting as a support leg assembly thereby) on top of the membrane 106.

The above-described feature of some embodiments of the present invention in which one or more leg assemblies 44 are not directly fastened to the rooftop structure 100 can be achieved by modifying the rail (s) 42 (by weight of the rails used with conventional roof- To make it easier to perform in a lightweight form. As described above, the roof-top rack system must be designed to withstand large loads (both upward and downward) in accordance with standard calculations, and consequently, conventional roof-top system rails become heavy enough to provide additional mechanical characteristics. The actual weight of the rails will depend on these features, such as design load, free span, material properties, installation conditions, and so on. The rails 42 of the present invention are also designed according to these standard factors, but in an installation where one or more of the leg assemblies 44 are not directly fastened to the roof structure 100, the rails 42 may be considerably lightweight. More specifically, the pressure equalization (through the gap between the individual photovoltaic devices 22 (see FIG. 1)) limits the overloaded upward load applied to the rail 42 and the non-penetrating leg assembly 44 The down load limits the span length involved. Next, it provides an inverse design load factor, so that the rail 42 has a reduced cross-sectional area / moment of inertia, and hence a weight.

For example, a simplified conventional roof leg system for holding a 3 foot by 5 foot photovoltaic element includes a beam (or rail) supported by a rooftop penetration support positioned in a span of 30 feet That is, the rooftop penetrating supports are spaced 30 feet relative to the length of the beam). When assembled on the roof, the beams are positioned 5 feet apart and provide a shared support for the individual photovoltaic devices. When it is assumed that an environmental maximum load of 30 psf upstream and 30 psf downstream is determined, the beam should be designed to meet the overall maximum load constraint of 30 psf under this example. If a load of 450 lbs / photovoltaic element is provided at 30 psf, a calculated maximum design load on a typical system of 150 lbs / ft will be generated. Under these conditions, each rail will then be designed to withstand a maximum moment of 16,754 ft-Ib.

However, in an embodiment of the present invention, it may be desirable to have the same design / installation environment constraints as those described above, but to have the same design / installation environment constraints that are located at a span of 10 feet from each other (and, as described above, When it is assumed that two unbonded leg assemblies 44 (equidistantly spaced) are provided, the calculated design load will change. In particular, due to pressure equalization effects (e.g. in spaced equivalent arrangement of photovoltaic devices) the upward design load is 5 psf, which implies an upward load of 75 lbs / photovoltaic device. When each photovoltaic element extends a distance of three feet along the rail 42, a maximum upward load of 25 lbs / ft on the rail 42 is determined and corrected to a maximum moment of 2,792 ft-Ib. A downward load of 30 psf should also be taken into account, but the maximum moment of the rail 42 of 1,875 ft-Ib will occur due to the presence of the intermediate unlocking leg assembly 44. Thus, under this example, the rail 42 is designed to withstand a maximum moment-distortion of 2,792 ft-Ib (the downward maximum moment of 1,875 ft-Ib is less than 2,792 ft-Ib), and the 16,754 ft- Values that are significantly less than the constraints are met by conventional roof rack system rails under the same installation environment. Thus, the rail 42 according to some embodiments of the present invention is considerably smaller than a conventional roof rack system rail and thus may be lightweight. For example, following the above-described simplified hypothesis, when the same materials and shapes are employed for a conventional roof-top rack system or a rail of the system of the present invention (e.g. 6063 T6 aluminum in the form of a box beam) The system rails will have a weight of 6.0 lbs / ft (to meet the 16,754 ft-Ib design constraint) while the rails 42 according to some embodiments of the present invention (to meet the constraint of 2,792 ft-Ib) Lt; RTI ID = 0.0 > lbs / ft. ≪ / RTI >

It will be appreciated that the above-described rooftop structure 100 is an example of a conventional structure. It can be changed in other buildings. For example, FIG. 6A illustrates another conventional rooftop comprising a support beam 122, a deck 124, and a membrane 126 secured to the deck 124 of the intermittent peening locations 128a-128d. Which provides a simplified view of the structure 120. However, in the structure of Fig. 6A, the peening positions 128a to 128d are unequally spaced. For example, the distance D ₁ between the first pinning position 128a and the second pinning position 128b is less than the distance D ₂ between the second pinning position 128b and the third pinning position 128c long. First, different pinning distances D ₁ through D ₃ are evaluated or determined and then employed to configure one or more mounting units 140 according to the present invention as shown in FIG. 6B. More specifically, mounting unit 140 includes rails 142 and a plurality of leg assemblies 144a through 144d. Rails 142 and leg assemblies 144a through 144d may assume any of the forms described above. However, the spacing between adjacent leg assemblies of the leg assemblies 144a through 144d is selected according to the corresponding pinning distances D ₁ through D ₃ . Thus, for example, the space between the first leg assembly 144a and the second leg assembly 144b corresponds to the pinning distance D ₁ between the first pinning position 128a and the second pinning position 128b do. Thereafter, in the final installation, each of the leg assemblies 144a-144d is coupled to the deck 124 (and optionally to the corresponding one of the support beams 122) through the membrane 126, The roof structure 120 is fixed to the roof structure 120. Alternatively, a smaller number of leg assemblies 144a-144d may be mounted directly to rooftop structure 120 (thereby allowing some of leg assemblies 144a-144d to act as mounting leg assemblies, Acting as an assembly. Regardless, since the through-fastener is located in the pre-applied piercing portion (i.e., the peening position 128a-128d) through the membrane 126, the resulting installation of the mounting unit 140 is characterized by minimal penetration It is erased. However, the mounting unit 140 (and photovoltaic elements (not shown) connected thereto) is fully supported relative to the rooftop structure 120 to offset the upward force and the downward force, and in a manner not associated with the rails 142 Allowing wave swinging of the membrane 126.

In some constructions, the mounting unit according to the invention is prefabricated (based on the peening distance which is the expected or determined membrane) and delivered to the installation site in its final shape. However, in other embodiments, the present invention incorporates one or more features that cause the installer to perform in-situ modification of the mounting unit as a function of the actual membrane peening distance encountered. For example, FIG. 7A illustrates a portion of another mounting unit 240 that is useful in accordance with the present invention and as part of a photovoltaic array (not shown). The mounting unit 240 is similar to the mounting unit described above and includes a rail 242 and a plurality of leg assemblies 244. The rails 242 include two or more rail segments 246, each holding one leg assembly of each of the rail assemblies 244. The rail segments 246 are configured to be slidably assembled together. For example, the first rail segment 246a acts as a primary rail segment and the remaining rail segments 246b through 246d are configured to be slidably received with respect to the first rail segment 246a. In this configuration, the rail segments 246 may then be positioned relative to one another during an installation process that positions the corresponding leg assemblies 244 in a predetermined space. For example, Figure 7b shows a mounting unit 240 that is assembled to a rooftop structure 100, wherein the rail segment 246 is configured such that the corresponding leg assemblies 244a through 244d are positioned in the pinning positions 108a through 108d Are arranged to be aligned with the respective pinning positions. 7C shows a mounting unit 240 installed on the roof structure 120. Fig. In other words, the rail 242 structure allows the installer to rapidly place the leg assemblies 244a through 244d in a normal arrangement with the membrane peening positions 128a through 128d.

Securing the rail segments 246 relative to one another can be accomplished in a variety of ways. For example, mechanical fasteners (not shown) may be mounted on the first rail segment 246a, once the second through fourth rail segments 246b through 246d have been spaced a predetermined distance between the leg assemblies 244 It can be employed to fix. In another embodiment, the rails 242 may be provided as a single body with one or more leg assemblies 244 movably assembled thereto (e.g., the leg assemblies 244 may be provided in a slot formed by the rails 242) ].

Regardless of how the leg assembly is connected to the rails, another embodiment according to the present invention provides a mounting unit that is different from the leg assembly structure. For example, FIG. 8A illustrates a portion of another mounting unit 300 that includes a rail 302, one or more mounting leg assemblies 304, and one or more support leg assemblies 306. The mounting leg assembly 304 can be assumed to be any of the shapes described above, each including a rigid leg 308 and a base 310.

Supporting leg assembly 306 also includes legs 312 and base 314, respectively. However, unlike the mounting leg assembly 304, the base 314 that cooperates with the support leg assembly 306 need not be adapted to facilitate use with a separate threaded fastener. Instead, the support leg assembly base 314 is configured to be positioned relative to the rooftop structure surface, and the support leg assembly 306 serves to counteract the downward force applied to the mounting unit 300. For example, the mass of the rail 302 and the corresponding photovoltaic element 22 (see FIG. 1) may be reduced by a downward force on the rail 302 at a location between adjacent ones of the mounting leg assemblies 304 . This downward force can be exacerbated by specific installations such as snowy climates. Under these circumstances, the inherent stiffness of the rail 302 may not be sufficient to completely offset the downward force, and as a result, the rail 302 will be curved between the mounting leg assemblies 304. However, the support leg assembly 306 serves to offset this potential problem by supporting the rail 302 (in contact with the roof structure surface). Thus, in some arrangements, regardless of the shape, each leg assembly 304, 306 has approximately the same length and an extension from the rail 302.

In some configurations, the one or more support leg assemblies 306 are configured to minimize the apparent resistance to upward movement of the corresponding bases 314 relative to the rails 302. From a reference point of view, an upward force can be applied to the base 314 of each of the support leg assemblies 306 by the wave crest rooftop membrane. In order to avoid the possibility that the support leg assembly 306 will lead to the rupture of the wobble roof top membrane and / or the possibility of inducing the wobble roof top membrane upwardly on the rail 302, 312 may be introduced by incorporating, for example, a spring 316. [ The spring 316 is disposed between the rail 302 and the base 314. In some embodiments, one or more segments 318 may be provided that further stabilize the spring 316 relative to the rail 302 and base 314. [ In addition, the legs 312 may incorporate two or more springs 316. Regardless, the spring (s) is similar to a constant force spring such that the force exerted on the base 314 by the spring 316 remains relatively constant despite the compression of the spring 316.

 The installation of the mounting unit 300 (as part of the photovoltaic array (not shown)) to the roof structure 100 is reflected in Figure 8b, which is shown by a fastener (not shown) through the membrane 106 And fixing the mounting leg assembly 304 to the rooftop structure 100. As described above, such a through connection does not create significant defects in the membrane 106 because it is applied to the pre-fabricated pinning position 108. However, the support leg assembly 306 is not secured to the roof structure 100 by the through-fastening. Instead, the bases 314 of each of the support leg assemblies 306 simply mate with the membrane 106.

As shown, the support leg assembly 306 is positioned along the rooftop structure 100 at points between adjacent ones of the peening positions 108. As a result, the mounting unit 300 can be pre-manufactured based on the pinning distance, which is the expected or estimated membrane, and / or the mounting unit 300 can be configured such that the leg assemblies 304, 306 slide relative to each other Thereby allowing the installer to implement a predetermined position of the leg assemblies 304, 306 during the installation process. Regardless, in the final installation, the mounting leg assembly 304 and the support leg assembly 306 act to reinforce the rail 302 (and the photovoltaic elements (not shown) associated therewith) against downward forces . That is, the rail assemblies 304,306 are mounted on the rails 302 relative to the roof structure 100 in the presence of an excessive lowering force (e.g., the snow accumulating on the photovoltaic elements carried by the mounting unit 300) Lt; / RTI > Conversely, resistance to movement of the mounting unit 300 in the presence of an upward force is achieved by the fastening interface of the mounting leg assembly 304 to the rooftop structure 100.

For example, under a windy condition, the securing properties of the mounting leg assembly 304 prevent the mounting unit 300 from moving relative to the rooftop structure 100. However, under this same condition, the support leg assembly 406 allows or accommodates the expected wave swing of the membrane 106 as shown in Figure 8c. More particularly, Fig. 8c shows a membrane 106 that is oscillating in zones 340a-c. The wavy swing membrane sections 340a-340c exert an upward force on the support leg assembly 306 in contact therewith (e. G., The first wavy swing membrane section 340a includes first and second support < Force an upward force on the base 314 of each of the leg assemblies 306a, 306b. Because the legs 312 of each of the support leg assemblies 306 are infeedable, the support leg assemblies 306 are pulled toward the rails 302 in response to this upward force, ) To oscillate in the expected manner and to apply the additional upward force to rail 302 at a minimum.

The optional retractable support leg assembly embodiments of the present invention are useful in many rooftop environments that may be intermittently fixed and thus may or may not include a membrane that is potentially wavy. More generally, the non-penetrating support leg assembly embodiment is useful in an installation environment where the anticipated downward force is greater than the anticipated upward force. As described above, the upward force added on the installed photovoltaic array 20 (see FIG. 1) is typically in the form of wind. Although the aforementioned gap or space between adjacent photodiodes 22 of the photovoltaic element 22 (see FIG. 1) enables pressure equalization, an upward force can be generated, which is based on various glow- Lt; / RTI > Conversely, downward forces are important in the function of the total mass or weight of the photovoltaic array 20, and the expected environmental conditions, such as rain or snowfall. This expected downward force may also be calculated. Under conditions where the calculated and anticipated downward force is calculated and exceeds the anticipated upward force, the mounting unit may then be designed to include the aforementioned support leg assemblies. In the final installation, the support leg assembly cancels the upward downward force, but does not cause any defects on the roof structure as no through-fastening is employed.

The photovoltaic array support system and associated mounting unit of the present invention provide significant improvements in the above-described configuration. The photovoltaic array is installed in a roof structure with a minimum through-hole shape. While the downward force is minimized (e.g., due to the mass of the photovoltaic array), the required stability is provided under the downward force condition. Also, a minimum number of relatively non-invasive roof penetrations is required. The photovoltaic array of the present invention is also well suited to lightweight commercial rooftop structures so that the accompanying wave swinging occurs in a manner that does not affect the overall stability of the installation or prevents the membranes from rupturing do.

Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosure.

Claims (26)

A photovoltaic array,
A plurality of photovoltaic power generation assemblies each including a photovoltaic stack,
A plurality of mounting units for supporting a photovoltaic assembly with respect to a rooftop structure,
Each mounting unit
A rail configured to hold at least two portions of the photovoltaic assembly,
And a plurality of leg assemblies extending from the rails in spaced-apart manner and each terminating at a foot opposite the rails,
At least one of the leg assemblies includes an inflatable leg configured to permit movement of the corresponding base toward the rails in response to an external force applied to the base
Photovoltaic arrays. The method according to claim 1,
The photovoltaic array is configured to mount to a commercial building rooftop structure comprising a membrane overlying a rooftop deck, wherein the membrane is configured such that the non-connection area of the membrane is capable of billowing upwardly from the rooftop deck in response to wind The legs intermittently connected to the roof deck and also the retractable legs are configured to accommodate the wave fluctuations of the non-connection zone at the time of final installation on the roof structure of the photovoltaic array
Photovoltaic arrays. The method according to claim 1,
At least two of the leg assemblies include rigid legs
Photovoltaic arrays. The method of claim 3,
The inflatable leg is located between the rigid legs along the length of the rail
Photovoltaic arrays. The method according to claim 1,
The inflatable leg includes a spring
Photovoltaic arrays. The method according to claim 1,
The length of each of the extending legs from the rail, including the inflectible legs in a non-deflected state,
Photovoltaic arrays. The method according to claim 1,
Each mounting unit further comprising a plurality of fasteners for coupling a selected one of the bases to the roof structure in a threaded manner,
At the final installation, at least the base cooperating with the inflatable leg is not coupled to the roof structure by the through-
Photovoltaic arrays. The method according to claim 1,
The rail has a size and weight selected to satisfy the maximum moment constraint determined to be greater of the installation environment up load calculation and the installation environment down load calculation
Photovoltaic arrays. The method according to claim 1,
The rail includes a first rail segment holding one of the leg assemblies having a rigid leg and a second rail segment holding a leg assembly having the inflatable leg,
The first rail segment and the second rail segment are configured to be selectively assembled with respect to each other
Photovoltaic arrays. The method according to claim 1,
The photovoltaic array includes a mounting unit, which holds a space between adjacent photovoltaic assemblies mounted thereon
Photovoltaic arrays. 10. The method of claim 9,
The first rail segment and the second rail segment are configured to be slidably assembled with respect to each other
Photovoltaic arrays. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

Images